Scientists Discover How Flu Attacks Immune System

If you've ever wondered how the flu virus succeeds at infecting so many people, a new study of mice may offer some insight.

The flu actually targets cells of the immune system that are best able to disarm the virus, according to the study. These first responders, known as memory B cells, produce antibodies that can bind to the virus and neutralize it. These cells also reside in the lung where they can protect against re-exposure to the virus.

Researchers found, however, that the flu virus attacks these memory B cells first to disrupt antibody production, allowing it to replicate more efficiently and prevent the immune system from mounting a second defense.

"We can now add this to the growing list of ways that the flu virus has to establish infection," study co-author Joseph Ashour, a postdoctoral researcher at the Whitehead Institute for Biomedical Research, said in an institute news release.

"This is how the virus gains a foothold," study co-author Stephanie Dougan, also a postdoctoral researcher in the lab of Whitehead member Hidde Ploegh, explained in the news release. "The virus targets memory cells in the lung, which allows infection to be established -- even if the immune system has seen this flu before."

Memory B cells, which have virus-specific receptors, are difficult to isolate. To address this issue, the researchers attached a fluorescent label to the flu virus, which allowed them to identify flu-specific B cells. They then used a cloning technique to create a line of mice with virus-specific B cells and cell receptors.

The study authors suggested that the infectious process of the flu is probably used by other viruses as well. "We can now make highly effective immunological models for a variety of pathogens," Dougan concluded. "This is actually a perfect model for studying memory immune cells."

Scientists note, however, that research with animals often fails to produce similar results in humans.

"This is research that could help with rational vaccine design, leading to more effective vaccines for seasonal flu," Ashour said. "It might even suggest novel strategies for conferring immunity."

If you've ever wondered how the flu virus succeeds at infecting so many people, a new study of mice may offer some insight.
The flu actually targets cells of the immune system that are best able to disarm the virus, according to the study. These first responders, known as...

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